It is necessary for automotive controls to obtain a measure of certain pressure parameters such as engine oil pressure, transmission fluid pressure or brake pressure. To this end it is customary to attach pressure sensors to the pressure line of interest. High pressure applications generally utilize a stainless steel diaphragm welded to a pressure port which attaches to the vehicle by a threaded fitting, for example. To permit welding, the pressure port is also comprised of stainless steel material. Such pressure ports are expensive due to the high cost of stainless steel relative to other materials and the difficulty of machining stainless steel.
Any pressure port design must accommodate a hermetic seal for the sensor (and therefore must be weldable to stainless steel) and must withstand the mechanical stresses such as pressure and torque to which the module will be subjected during installation and subsequent use. Proposed alternatives to the one-piece stainless steel pressure port have included multiple piece stainless steel pressure ports. Although this reduces the cost of the pressure port, the cost of the complete sensor is increased due to additional pieces to assemble and the reliability is decreased.
It is desirable, however, to reduce the pressure port cost by reducing the stainless steel content and reducing the overall cost of the pressure sensing module while maintaining high reliability.